I knew someone who tapered down to 1 ounce of methadone and she stayed on that dosage for two years. Methadone is long acting, long living and slowly starts eating away in your bone marrow and gets stuck in your fatty tissue.
My friend went in for a drug test, she hadn't used for 11 days, she was overweight, had a low metabolism and in her 40's and the test came back positive Depending on the dosage, frequency, metabolism, immune system age of your friend - I don't know that - most of the people I know who have used it for a ample amount of time - look sick - gain weight - they look puffy - and their skin looks flat matte -
High to moderate dependency is supposed to last 6 to 12 days before it gets out of your system, the effects it has damaged to the internal organs may take years. I'm not a doctor, so don't quote me, just what I know from personal past experiences. I had a choice to use it for medical purposes at one point in my life and I declined. Another friend I knew on meth developed a collapsed lung then phenomnia then died.